Container events - Brushy Suite

Containers emit events when observers are registered via observe(). This powers @brushy/di-monitor and custom telemetry.

const unsubscribe = container.observe((event) => {
  console.log(event.type, event.token, event.details);
});

// Later
unsubscribe();

Event emission is optimized away until the first observe() call. Attaching a monitor or observer enables the event path for subsequent operations.

Event types

interface ContainerEvent {
  type: "register" | "resolve" | "error" | "import" | "clear";
  token?: Token;
  timestamp: number;
  details?: unknown;
}

Type	When	Typical `details`
`register`	`register` / `registerMany`	`{ config }`
`resolve`	Successful `resolve` / `resolveAsync` / `resolveInScope`	`{ success: true, source, async?, scoped? }`
`error`	Failed resolve	`{ error, message, async? }`
`import`	`container.import()`	`{ sourceContainer, targetContainer, providersCount, options }`
`clear`	`clearRequestScope` / `clearScopedInstances`	`{ scope }`

Performance note

When no observers are attached, resolve uses a fast path with a monomorphic last-token micro-cache. After observe() is called, every resolve goes through the event bus. For production monitoring, prefer @brushy/di-monitor with filtered eventTypes instead of ad-hoc observe handlers on hot paths.

Custom observers

container.observe((event) => {
  if (event.type === "error") {
    metrics.increment("di.resolve.error");
  }
});

Container monitor: buffered history and stats
Debug API: exportProviders for introspection